Method for alignment calibration of an inertial measurement unit in a head-worn apparatus

Abstract

A method for alignment calibration of an inertial measurement unit contained in a head-worn apparatus. The method includes: wearing an apparatus on the head of a user; performing a static calibration stage including determining a misalignment of a first sensitive axis of the inertial measurement unit with respect to a direction of gravity while the user holds their head statically, looks straight ahead and horizontally.

What is claimed is: 
     
         1 . A method for alignment calibration of an inertial measurement unit contained in a head-worn apparatus. The method including:
 (A) wearing an apparatus on a head of a user;   (B) performing a static calibration stage including determining a misalignment of a first sensitive axis of the inertial measurement unit with respect to a direction of gravity while the user holds their head statically, looks straight ahead, and horizontally.   
     
     
         2 . The method for calibrating an inertial measurement unit according to  claim 1 , further comprising:
 (C) performing a dynamic calibration stage including determining a misalignment of a second sensitive axis of the inertial measurement unit while the user tilts their head to the left and/or right or the user nods their head up and/or down.   
     
     
         3 . The method for calibrating an inertial measurement unit according to  claim 1 , further comprising:
 (C) performing a mathematical correction of a misalignment of a second sensitive axis of the inertial measurement unit using apparatus-specific alignment information.   
     
     
         4 . The method for calibrating an inertial measurement unit according to  claim 3 , wherein, in step (B), apparatus-specific alignment information is provided for the static calibration stage and, as a result of step (B), updated apparatus-specific alignment information is provided for step (C).